The subcutaneous implantable cardioverter defibrillator (S-ICD System™) from Boston Scientific Corporation has been commercially available in many countries for several years now. The commercial system and implant comprises a pulse generator implanted on the left side of the chest, near the left axilla, with a lead extending from the left axilla to near the xiphoid process and then superiorly just to the left of the sternum, over the ribs. The implant method has been updated several times from early implants to current practices.
The most common implant practice has been to use a three incision method. A tunneling tool is advanced from a xiphoid incision to an incision at the left axilla. A long loop of suture is used to secure the lead distal tip to the tunneling end of the tunneling tool. The tunneling tool is slowly withdrawn via the xiphoid incision, pulling the lead into the xiphoid-axillary tunnel by the suture until the distal end of the lead exits the xiphoid incision. Next, the tunneling tool is advanced from the xiphoid incision to an upper sternal incision near but generally inferior to the manubrium, with the suture still attached. The suture loop should be long enough to allow this parasternal tunnel to be formed without the lead having to go into the tissue.
After the distal dip of the tunneling tool exits the upper sternal incision, the suture loop is cut and the ends of the suture loop extending out of the upper sternal incision are grasped with a forceps. The tunneling tool is removed. The distal tip of the lead is pulled into the parasternal tunnel using the suture grasped by the forceps until the distal tip of the lead exits the upper sternal incision. The suture loop is removed and discarded. The lead is sutured to the fascia at the upper sternal incision, and a suture sleeve is placed over the lead near the xiphoid incision to provide additional fixation.
A two incision approach has also been considered and used. In a two incision approach, the lead may be pulled from the left axilla through a subcutaneous tunnel to the xiphoid incision similar to the three incision approach. An introducer with a sheath thereon may be advanced from the xiphoid incision superiorly alongside the sternum. The introducer is then removed while holding the sheath in place, with the sheath acting to preserve the tunneled route for placement of the lead. The lead is inserted through the sheath, and the sheath is removed while holding the lead in place. A suture sleeve is used to anchor the lead at the xiphoid incision. The two incision approach does not include an upper sternal incision, thereby reducing the number of scars, improving the cosmetic outcome and potentially reducing infection risk.
In each of these methods of implantation, there is a significant amount of time spent tying knots with sutures to, for example, couple together the lead with the implantation tool, to tie to the lead itself for the “pulling” steps, to suture the lead down to the fascia, and to attach the lead and suture sleeve combined to the fascia. Reducing the amount of knot tying would reduce procedure time.
When first introduced, an anticipated benefit of the S-ICD System™ was that of reduced procedure time. Some implanters have been able to see benefits in that regard. However, years of experience have shown that with the methods described above, even after several rounds of enhancement and continued physician training updates, procedure time benefits have not been broadly realized. There is continuing interest in new and different methods that can reduce procedure time.